1. Field of the Invention
The present invention relates to a noncontact tonometer for measuring intraocular pressure by blowing fluid such as air against the cornea of a subject eye to deform it and detecting and analyzing a change in index light projected onto the cornea.
2. Description of the Related Art
Noncontact tonometers have the advantages of no eye contact and requiring no eye-drop anesthetic and so on, thus being broadly used in the field of ophthalmology for screening to detect glaucoma caused by high intraocular pressure. When intraocular pressure is more than a predetermined value, close examinations including an eyeground examination and campimetry are performed.
An automatic positioning system is disclosed in Japanese Patent Laid-Open No. 9-84760 assigned to the same assignee as this application, in which an index image projected on a subject eye is sensed to determine the relative position between the eye and a measuring section, and a stage is controlled by motor drive.
Also, noncontact tonometers capable of full automatic measurement are going into practical use in which upon completion of predetermined times of measurements, the measuring section moves automatically to the other eye that has not yet been measured to position it and makes a predetermined number of measurements.
With the related-art noncontact tonometers, however, if eyelashes are caught on the cornea during the measurement, the resistance of the eyelashes prevents the cornea from being sufficiently deformed, so that even when the actual intraocular pressure is within a normal range, the reading sometimes indicates a higher value. Also when the fixation of the subject eye is out of place, the reading shows a lower value than the actual intraocular pressure, but only rarely. Therefore, when the intraocular pressure is higher or lower than a predetermined value, examiners perform remeasurement for confirmation.
In a case with a fully automatic system in which a measuring position is sensed, positioned automatically, and a predetermined number of measurements are sequentially performed for both eyes, when a predetermined number of measurements for one eye have been completed, the measuring section is moved to the other eye that has not yet been measured and performs a predetermined number of measurements. Therefore, the measuring section must be moved again if remeasurement for the first subject eye is necessary, thus preventing the reduction in the time required for measurements. Also, since the measuring operation has been completed, the measurement for confirmation is sometimes forgotten.